The presence of water in a vehicle fuel system may cause extensive damage to vital engine and fuel system components. The integrity of fuel injectors, pumps, filters, and fuel s may all be subject to degradation if a water-in-fuel condition is allowed to persist. The presence of a water-in-fuel condition may lead to reduced overall lubricity of engine components which may result in scoring of pump plungers and needles. Furthermore, larger amounts of water in a fuel tank may produce an environment at the fuel-water interface that is conducive to microbial growth which may result in the clogging of filters and/or corrosion of metal engine and fuel system components. Overall engine performance may also be negatively impacted as the presence of water may reduce the efficiency of combustion processes.
Today, many vehicle fuel systems may utilize a fuel-water separator to remove water from a fuel system and thereby reduce the likelihood of engine and/or fuel system damage. Often times, an auxiliary water tank is arranged to receive water that has been removed from the fuel system by the fuel-water separator. Typically, a sensor (optical, thermal, or electric conductivity, for example) is coupled to an inner surface of an auxiliary water tank or to an inner surface of a fuel-water separator reservoir at a threshold water level along the vertical axis (when the vehicle is on level ground) of the auxiliary water tank or fuel-water separator reservoir that corresponds to a pre-determined threshold volume of water that has been separated from the fuel system. In other words, when the sensor detects that a threshold level of water has been exceeded, a raw voltage signal may be produced by the sensor that may result in a driver notification via an indicator light or indication sound that informs the driver of a water-in-fuel condition.
The inventors herein, however, have recognized that a binary water-in-fuel detection system such as the one described above, may determine the presence of a water-in-fuel condition inaccurately. During periods of transient vehicle operation such as accelerating, hard braking, turning, parking on a grade, etc., sloshing of water may occur in the vicinity of a sensor that may temporarily cause the sensor to be submerged in water when the overall volume of water within an auxiliary water tank or a fuel-water separator reservoir may be less than the threshold volume of water indicative of a water-in-fuel condition. A transient raw voltage signal may then be produced that results in a false notification of a water-in-fuel condition to the driver of the vehicle
In one approach, a method for operating a vehicle having a fuel system that may be contaminated with water is provided. The method comprises adjusting an operating parameter in response to a relative amount of high and low readings from a water-in-fuel sensor coupled in the fuel system. In this way, by using a plurality of high and low readings to determine whether a water-in-fuel condition is present, more robust and reliable determinations of a water-in-fuel condition may be realized during both steady state and transient vehicle operating conditions.